Compressor side inlet with improved aerodynamic performance and reduced manufacturing complexity

ABSTRACT

An air plenum is configured to direct air into a centrifugal compressor impeller in an ACM compressor. The air inlet plenum has a cylindrical outer wall, a forward circular end wall, and a rearward circular end wall. An air inlet radially extends from the cylindrical outer wall and is in flow communication therewith. An aperture in forward circular end wall is configured to seal receive about a rotating shaft. An aperture in rearward circular end wall is configured to receive the rotating shaft and allow air flow therethrough about the rotating shaft. A rectangular baffle extends radially inward from the cylindrical outer wall at a circumference thereof opposite the air inlet. The rectangular baffle may extend between the forward and rearward end walls.

BACKGROUND OF THE INVENTION

The present invention relates generally to compressors, and morespecifically to an air inlet system for a centrifugal compressor of anair cycle machine for aircraft environmental control system or a gasturbine engine compressor.

Centrifugal compressors of air cycle machines for aircraft environmentalcontrol systems may be mounted on the mid-portion of a rotating shaftbetween a turbine and a fan. This configuration is commonly referred toas a three-wheel Air Cycle Machine (ACM). It is typical of an ACM thatthe energy gained in turbine is used to drive a compressor and a fan.All three wheels (turbine, compressor, and fan) may be disposed on acommon shaft of an ACM or three-wheel machine. The fan may convey acooling air stream branched off from ambient air through a cooling shaftin which primary and main heat exchangers may be disposed.

For three-wheel ACMs, the compressor is usually mounted on themid-portion of the rotating shaft between the turbine and the fan; thistypical configuration may result in a geometrically complicated sideinlet design. The air inlet may need to first direct the flow radiallyinward from one side, then split the flow around the rotating shafttowards two sides, and simultaneously turn the flow into an axialdirection for entry into an impeller eye of a compressor.

Since a compressor's overall performance may be sensitive to the inletflow pattern and inlet pressure loss, various inlet plenumconfigurations such as a double-lobed plenum and array of inlet guidevanes (IGVs) have been used for aircraft environmental controlapplications. Such a configuration is shown in FIG. 1. Double-lobedplenum 200 has inlet 202 and IGVs 206. IGVs 206 extend in the directionof air flow from inlet 202 to radial outlet 212. Bypass channels 204 maybypass inlet air from radial outlet 212 as shown. Two lobes 208 are inplenum 200 about radial outlet 212 on a side opposite flow inlet 202.Lobes 208 extend inwardly and meet at location 210, proximate radialoutlet 212 and opposite inlet 202.

As can be seen, there is a need for minimizing the inlet aerodynamicloss of an inlet plenum and promoting inlet flow uniformity whileproviding a means to reduce the manufacturing complexity of the plenumfor an ACM.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a centrifugalcompressor of an ACM for an aircraft environmental control system isprovided. The compressor has a rotatable cylindrical shaft with animpeller having blades radially extending outward therefrom. An airinlet plenum has a cylindrical sidewall, a first end wall, and a secondend wall. The first end wall has an aperture configured to besubstantially sealed about the rotatable cylindrical shaft. The secondend wall has an outlet in flow communication with the impeller about therotatable shaft. An air inlet extends radially outward from thecylindrical sidewall and is in flow communication with the air inletplenum. A baffle extends radially inward from the cylindrical wallapproximately 180° from the air inlet.

In another aspect of the present invention, a centrifugal compressor isprovided having a shaft with a longitudinal axis and a gas turbineengine configured to rotate the shaft about the longitudinal axis. Theshaft has an impeller with blades extending radially therefrom. An airinlet plenum has a portion about the shaft between the gas turbineengine and the impeller. The air inlet plenum is configured to firstdirect the flow of inlet air radially inward to the shaft from one sideof the shaft and split a portion of the flow of inlet air around therotating shaft while simultaneously turning the flow of inlet airparallel to the longitudinal axis of said shaft for entry into theimpeller. The portion of the plenum about the shaft has a cylindricalouter wall with an air inlet portion extending therefrom in a radialdirection from the shaft. A rectangular baffle extends radially inwardfrom the cylindrical outer wall of the plenum toward the shaft. Therectangular baffle is on an opposite side of the cylindrical outer wallthan the air inlet portion and extends the cylindrical outer wall in adirection substantially parallel with the longitudinal axis of theshaft.

In yet another aspect of the present invention, an air inlet plenum isprovided to direct air into a compressor impeller. The air inlet plenumhas a cylindrical outer wall, a first circular end wall, and a secondcircular end wall. An air inlet radially extends from the cylindricalouter wall and is in flow communication therewith. An aperture in thefirst circular end wall is configured to sealing receive a rotatingshaft. An aperture in the second circular end wall is configured toreceive the rotating shaft and allow air flow between the secondcircular end wall and the rotating shaft. A rectangular baffle extendsradially inward from the cylindrical outer wall at a circumferencethereof opposite the air inlet. The rectangular baffle extends betweenthe first and second end walls.

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdrawings, description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective sectional view of an air plenum of the priorart;

FIG. 2 is a schematic sectional view of a centrifugal compressor of anACM according to an embodiment of the present invention;

FIG. 3 is a perspective sectional view of an aspect of an air plenumaccording to an embodiment of the present invention;

FIG. 4 is a perspective sectional view of another aspect of an airplenum according to an embodiment of the present invention;

FIG. 5 is a side cross-sectional view of a section of an air plenumaccording to an embodiment of the present invention showing air flowpaths therethrough; and

FIG. 6 is a front cross-sectional view of a section of an air plenumaccording to an embodiment of the present invention showing air flowpaths therethrough.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description is of the best currently contemplatedmodes of carrying out the invention. The description is not to be takenin a limiting sense, but is made merely for the purpose of illustratingthe general principles of the invention, since the scope of theinvention is best defined by the appended claims.

Various inventive features are described below that can each be usedindependently of one another or in combination with other features.However, any single inventive feature may not address any of theproblems discussed above or may only address one of the problemsdiscussed above. Further, one or more of the problems discussed abovemay not be fully addressed by any of the features described below.

For three-wheel Air Cycle Machines (ACMs), the centrifugal compressormay be mounted on the mid-portion of a rotating shaft between a turbineand an impeller or fan. This configuration may result in a geometricallycomplicated side inlet design, which may be required to first direct theflow of intake air through an air inlet radially inward from one sideand then split the air flow around the rotating shaft and simultaneouslyturn the air flow to an axial direction for entry into the impeller eye.Since compressor overall performance may be sensitive to the inlet flowpattern and inlet pressure loss, the configuration of an air plenum maybe critical. Embodiments of the present invention may provide a meansfor enhancing the aerodynamic performance of an air delivery system tothe impeller without increasing manufacturing complexity and costs.

FIG. 2 shows ACM compressor 100. Rotatable shaft 104 may extend from aforward end 106 to a rearward end 107. A gas turbine engine, not shown,may provide rotational power to shaft 104 at forward end 106. Air plenum102 is shown having an air inlet 120 in a lower cylindrical portion 122thereof. The lower cylindrical portion 122 may extend upward to a flaredportion 124 of or air inlet 122. Flared portion 124 may extend upward tocylindrical outer wall 132 which may circumscribe shaft 104 proximateimpeller 108. Air plenum 102 may have a circular or rounded forward wall133 which may seal with rotatable shaft 104 enclosing an axial end ofcylindrical outer wall 132. Rearward wall 135 may partially enclose theother axial end of cylindrical outer wall 132. Rearward wall 135 hasaperture 126, which has a diameter greater than the diameter ofrotatable shaft 104 allowing air to exit air plenum 102 and enterimpeller 108. Impeller 108 compresses the inlet air which may exitthrough diffuser 137 to compressor outlet 110. Baffle 130 is showndepending inward from outer wall 132 and may be normal to the axis ofcompressor 100. Baffle 130 may be comprised of a solid material havingno perforations or apertures. Such a configuration may prevent airflowing thereto from flowing around the inner surface of outer wall 132.

FIG. 3 shows a perspective view of air plenum 102. Air plenum 102 isconfigured to direct air axially about rotatable shaft 104 intocompressor impeller 108. Air plenum 102 may have cylindrical outer wall132 with circular forward wall 133 and circular rearward wall 135partially enclosing axial ends thereof. An aperture 134 in circularforward wall 133 may be configured to sealing receive rotatable shaft104. An aperture 126 in rearward circular wall 135 is configured toreceive rotatable shaft 104 and has a greater diameter than rotatableshaft 104 to allow air flow between rearward circular wall 135 androtatable shaft 104. Air inlet 120 radially extends from cylindricalside wall 132 and is in flow communication therewith. Air inlet 120 mayhave lower cylindrical portion 122 extending upward to flared portion124 of or air inlet 122. Flared portion 124 may extend upward tocylindrical side wall 132. Rectangular baffle 130 extends radiallyinward from cylindrical side wall 132 at a circumference thereofopposite or 180° from air inlet 120. Rectangular baffle 130 may extendbetween and may join circular forward wall 133 and circular rearwardwall 135. Advantageously, baffle 130 may extend at least one forth thedistance from cylindrical side wall 132 and aperture 134 in forward wall133.

FIG. 4 shows a perspective view of air plenum 202. Air plenum 202 mayhave a similar configuration as air plenum 102 and at least one inletguide vane 136. Guide vane 136 is configured to direct the flow of inletair radially toward rotatable shaft 104. Guide vane 136 may be in aplane parallel with a plane of baffle 130 and may be substantiallywithin flared portion 124 of air inlet 120.

FIG. 5 shows air flow paths 140 through a side cross-sectional view ofair plenum 102. Air enters air plenum 102 through air inlet 120 in asubstantially radial orientation with respect to rotatable shaft 104.The air flows upward through lower cylindrical portion 122 and intoflared portion 124 of air inlet 120. In flared portion 124 air flowpaths 140 begin to diverge toward impeller 108 and about the surface ofrotatable shaft 104. Within cylindrical side wall 132, air flowscircumferentially about its inner surface toward baffle 130 and axiallytoward impeller 108. Baffle 130 may prevent the air flow pattern 140from swirling about the inside surface of cylindrical sidewall 132 ofair plenum 102 and force the flow to turn axially with respect torotatable shaft 104 sooner and enter impeller 108 earlier and thuspromote the inlet flow uniformity and reduce the inlet pressure loss.Air flows axially through aperture 226 and into compressor outlet 110.Forward wall 133 may seal the opposite axial end of cylindrical sidewall 132 with shaft 104, forcing all inlet air through aperture 126 inrearward wall 135.

FIG. 6 shows air flow paths 140 through a front cross-sectional view ofair plenum 102. Air enters air plenum 102 through air inlet 120 in asubstantially radial orientation with respect to rotatable shaft 104.The air paths 140 are upward through lower cylindrical portion 122 andinto flared portion 124 of air inlet 120. In flared portion 124, airflow paths 140 begin to diverge toward aperture 126 in rearward wall 135and about the surface of rotatable shaft 104. Within cylindrical sidewall 132, air flows circumferentially about its inner surface towardbaffle 130 and axially toward aperture 126. Baffle 108 may prevent theair flow pattern 140 from swirling about the inside surface ofcylindrical sidewall 132 of air plenum 102 and force the flow to turnaxially with respect to rotatable shaft 104 sooner and enter impeller108 earlier and thus promote the inlet flow uniformity and reduce theinlet pressure loss.

As shown in FIGS. 5 and 6, baffle 130 in cylindrical side wall 132 mayreduce pressure loss in air flow 140 as it flows from air inlet 120 andout of aperture 126. Baffle 130 may also improve the flow uniformity ofair flow 140 at the plenum exit or the impeller entrance at aperture126.

Plenum 102 with circular or cylindrical side wall 132 having a singlerectangular baffle 130 may be casted easily and baffle 130 may preventthe flow 140 from swirling inside plenum 102 and force the flow to turnaxially toward aperture 126 earlier and enter the impeller earlier andthus may promote inlet flow uniformity to the impeller and reduce theinlet pressure loss.

It should be understood, of course, that the foregoing relates toexemplary embodiments of the invention and that modifications may bemade without departing from the spirit and scope of the invention as setforth in the following claims.

1. A compressor comprising: an impeller; an air inlet plenum having asidewall, a first end wall, and a second end wall; said first end wallhaving an aperture configured to be substantially sealed about arotatable shaft; said second end wall having an outlet in flowcommunication with said impeller about said rotatable shaft; an airinlet extending radially outward from said sidewall and being in flowcommunication with said air inlet plenum; and a baffle extendingradially inward from said sidewall approximately 180° from said airinlet.
 2. The compressor of claim 1 wherein said baffle is rectangular.3. The compressor of claim 1 wherein said baffle is solid.
 4. Thecompressor of claim 1 wherein said baffle extends between said first andsaid second end walls.
 5. The compressor of claim 1 wherein said baffleextends at least one half the distance from said sidewall to said shaft.6. The compressor of claim 1 wherein said air inlet has at least oneguide vane configured to direct the flow of inlet air radially towardsaid shaft.
 7. The compressor of claim 6 wherein said guide vane is in aplane parallel with a plane of said baffle.
 8. An air cycle machinecompressor comprising: an air inlet plenum having a portion about ashaft between a gas turbine engine and an impeller; said air inletplenum being configured to direct the flow of inlet air radially inwardto the shaft from one side of the shaft and split a portion of the flowof inlet air around the rotating shaft while simultaneously turning theflow of inlet air parallel to a longitudinal axis of the shaft for entryinto the impeller; said portion of said plenum about said shaft having acylindrical outer wall; said cylindrical outer wall of said air inletplenum having an air inlet portion extending therefrom in a radialdirection from the shaft; and a rectangular baffle extending radiallyinward from said cylindrical outer wall of said plenum toward the shaft,said baffle being on an opposite side of said cylindrical outer wallthan said air inlet portion and extending said cylindrical outer wall ina direction substantially parallel with the longitudinal axis of theshaft.
 9. The air cycle machine compressor of claim 8 further comprisinga guide vane in said air inlet portion configured to direct inflowingair radially toward said shaft.
 10. The air cycle machine compressor ofclaim 8 wherein said portion about said shaft has sidewalls radiallyextending inward from said cylindrical outer wall toward said shaft,said rectangular baffle extends between said sidewalls.
 11. The aircycle machine compressor of claim 8 wherein said baffle extends at leastone half the distance from said cylindrical outer wall to said shaft.12. The air cycle machine compressor of claim 8 wherein said portion ofsaid plenum is configured to provide a substantially uniform flow rateof air about the circumference of said shaft for entry into saidimpeller.
 13. An air plenum configured to direct air into a compressorimpeller comprising: a cylindrical outer wall; a first rounded end wall;a second rounded end wall; an air inlet radially extending from saidcylindrical outer wall and being in flow communication therewith; anaperture in said first rounded end wall configured to sealing receive arotating shaft; an aperture in said second rounded end wall configuredto receive the rotating shaft and allow air flow between said secondrounded end wall and the rotating shaft; and a baffle extending radiallyinward from said cylindrical outer wall at a circumference thereofopposite said air inlet, said rectangular baffle extending between saidfirst and second end walls.
 14. The air plenum of claim 13 wherein saidbaffle extends at least one half the distance from said cylindricalouter wall to said aperture in said first circular end wall.
 15. The airplenum of claim 13 wherein said air inlet has at least one rectangularguide vane in a plane parallel with a plane of said baffle.
 16. The airplenum of claim 13 being configured to intake air from said air inletand supply air to said aperture in said second circular end wall with asubstantial even distribution of air flow about a circumference of saidaperture in said second side wall.
 17. The air plenum of claim 13wherein said air inlet has a tapered portion radially extending fromsaid cylindrical outer wall and a cylindrical portion extending radiallyoutward from said tapered portion.